/Engine/Source/Runtime/Renderer/Public/ScreenPass.h
Texture viewport min / max in normalized UV coordinates, with respect to the texture extent, adjusted by a half pixel offset for bilinear filtering. Useful for clamping to avoid sampling pixels on viewport edges; e.g. clamp(UV, UVViewportBilinearMin, UVViewportBilinearMax);
typedef zzNextMemberIdUVViewportSizeInverse zzMemberIdUVViewportBilinearMin